Improvement in sgrew-propellers



UNITED STATES omen HARRY A. OROSSLEY Awesome-w. FRENCH, or cnEvEnAivD,onto.

IMP'RQVEMEN'T m"s'eREwm'nomLms;,

I Specification formingpart of Letters Patent Biol 183,373, datedOctober 17 1876, application filed Septemberfll, 1876.

To allwhom itmay concerm, v.

Be it known that we, HARRY A. H RossLEY and GEORGE W. FRENCH, ofCleveland, in the county of Ouyahoga and State of Ohio, have inventedcertain new and useful Improvements in Screw-Propellers, of which thefollowing is a full, clear, and exact descrip tion.

This invention consists in a screw-propeller the blades whereof areformed with concave faces and correspondingly convex backs, corrugated,crimped, fluted, or not, as desired, to-

augment the resisting surface, having their outer ends reversely curved,and set on the hub inthe same or different planes, and at the same ordifferent angles or pitch, whereby the resistance is so increased thatas the vessel progresses its motion is accelerated without increasingthe proportionate number of revolutions of the wheels, and whereby, whenthe vessel is to be backed, the blades act to throw the water outwardlyfrom the sides, instead of against the stern, of the vessel,substantially as hereinafter specified.-

In the drawings illustrating this invention, Figure 1 is a perspectiveview. Fig. 2 is a front view; Fig. 3, a rear view. Figs. 4, 5, and 6 arecentral longitudinal sections of the several forms of the blades.

A B indicate blades of a screw-propeller having in common a concaveface, correspondingly-convex back, and reversely-curved'ends or tips,and securedto the hub D in the same plane and at the same pitch orangle, or alternately in different planes and pitches or angles, for apurpose hereinafter referred/r0. In blade A its edge from a to bisstraight and thickened to afford better and greater resistance inbacking. Its edge from a to a is somewhat parabolic and sharp, so as toafford the least resistance in entering the water. Its face 0 isconcave, but extending to the edge a b on a level. Its back 01 is of aconvexity corresponding to the concavity of the face, and its outer endor tip 0 is curved reversely to the face and back curves from the points1 to 2, or front to, or nearly to, rear edges, so as to gather the waterand throw it outwardly from the stern on opposite sides of alongitudinal line parallel with the wheel or propeller shaft, wherebythe vessel is made to reversely or diagonally across the blades, as isbest suited for the vessel to which they are to be applied relatively toits destined speed.

It will be noticed that the concavity and convexity are not uniform orregular throughout the blades. For illustration, the edges a b and a a"are in the same plane, and the edge a b is in the same plane withthecenter of the concavity, while edge a a is in a higher plane. Theback is convex both longitudinally and transversely, and thisconstruction will be found best adapted for advantageous action inentering and leaving the water.

In the blade B the edge a b is curved but slightly, its center beingbeyond the blade, and its edge a a is elliptical, or nearly so,both'edges being sharpened. Its concavity c has its surrounding edges orlimits convexly formed, so as to most readily shed the water. Its back dis perfectly convex, except at its end or tip 0, which is reverselycurved from points 1 to 2, or from front to, or nearly to, rear edges. Ablade of the shape of blade A should be set on the hub at a less pitchor greater angle than such a one as B, in order to obtain the bestresults in motiona necessity arising from the shape of such blades.

In the blade 0 is shown a feature-namely, the corrugations, flutes, orfurrows fwhich may be employed in either of the other blades.

They are shown ina blade of ordinary form,

in order to illustrate the manner in which better results may beobtained in forward or backward motion with such blades. corrugationsconstitutes a concavity in which the water is gathered, and is deepestat its end g, where the most power is to be gained, and graduallydecreases rearwardly to such extent that that edge of the blade isalmost straight, whereby the water is readily shed. A blade thusgrooved, fluted, or-otherwise furrowed will present the entire tip orouter end from front to rear in a shape corresponding to that marked 6in the other blades, and thus obtain the advantages inherent therein.

Each of such After a vessel has got under way, could the pitch or angleof the blade be changed, greater speed might be obtained withoutincreasing the number of revolutions of the propeller. In a measure toaccomplish this the blades should be alternately set on the hub indifl'erent planes. If three blades be used, two should be set at thesame'angleor pitch forward, and the other rearward and atan increasedpitch or less angle. The varying resistance thus aiforded gives theresult.

What we claim is-- 1. A propeller-blade having one edge straight, ornearly so, and the other parabolic or elliptical, a concave face, convexback, and a reversely-curved tip or edge, substantially as and for thepurpose specified.

2. The blades of a screw-propeller, having 4. A propeller-blade havingcorrugations,

flutes, or grooves, decreasing gradually in depth rearwardly, and itstip or edge curved backwardly, substantially as shown and described.HARRY A. GROSSLEY. GEORGE W. FRENCH. Witnesses:

J OHN '1. DRAM, EDMOND F. ATIIERTON.

